Download time calculator

How to use the download time calculator

Fill in two boxes, and a third if you know your connection well.

1. File size. Copy it from the store page, the download dialog or the file listing. Choose MB, GB or TB to match.
2. Download speed. Run a speed test and take the download figure, in Mbps. If it's shown in Gbps, pick Gbps instead.
3. Real-world speed (optional). It starts at 100%. If you know your downloads only reach part of the speed test, enter that share.

The result gives the time, then the same speed in megabytes per second. Game launchers and browsers show that second number while a download runs, so you can compare the two as it goes.

A worked example. A game page lists 50 GB, and your speed test shows 100 Mbps. The calculator turns 50 GB into 50,000 MB and then 400,000 megabits. Divided by 100, that's 4,000 seconds: about 1 hour 7 minutes, or 12.5 MB/s on the launcher's counter.

The download time formula

Three steps, all of them multiplication or division:

1. Size to megabytes. A gigabyte is 1,000 MB, and a terabyte is a thousand gigabytes.
2. Megabytes to megabits. Multiply by eight, since a byte is 8 bits.
3. Megabits to seconds. Divide by your speed in Mbps. Divide the answer by 60 for minutes, or 3,600 for hours.

Written as one line: seconds = size in megabytes × 8 ÷ download speed in Mbps.

These are decimal units: a megabyte is 1,000,000 bytes, and a megabit is 1,000,000 bits. That's how speed tests and internet plans count.

Some software counts sizes in binary units but still writes "GB". Apple names older systems that did, such as iOS 10 and earlier and OS X Leopard and earlier. A binary gigabyte is 1,073,741,824 bytes, about 7% more than a decimal one. If your size came from software like that, allow a little extra.

If you set a real-world share, the calculator multiplies your speed by it before dividing. At 60%, a 100 Mbps line counts as 60 Mbps, and the same 50 GB takes about 1 hour 51 minutes.

Download times for common sizes

Times at a steady, full speed, rounded. Each column is one connection speed.

For scale, the FCC's minimum benchmark for fixed broadband is 100 Mbps down. A line at that benchmark matches the 100 Mbps column.

Your speed in Mbps against the MB/s on screen

The most common surprise isn't the time. It's the speed counter.

Internet plans and speed tests use megabits per second. Browsers, game launchers and download managers usually show megabytes per second. The second number is eight times smaller, so a 300 Mbps plan shows about 37.5 MB/s at best.

If your counter sits near the right column, your download is running at full speed. For any other value, use the Mbps to MB/s converter.

Why downloads run slower than your plan

The calculator's first answer is the ceiling. Real downloads rarely hold it from start to finish:

• Overhead on every packet. Data travels in small packets, each with its own addressing. RFC 6349, the IETF's guide to testing transfers, puts the best a 100 Mbps wired link can carry at 94.9 Mbps.
• Wi-Fi. Distance, walls and neighbours' networks cut speed before your plan's limit does. A cable to the router is the fastest fix.
• The server's side. A store or website sends each person only so much at once, and busy launch days slow everyone.
• Other people at home. Streams, calls and backups share the same line.
• The disk. Very fast lines can outrun an old hard drive, and big games also spend time unpacking after the download.

That's what the real-world field is for. If you've watched a download before, convert its MB/s to Mbps by multiplying by eight. Divide that by your speed test's figure, multiply by 100, and enter the result.

Planning a big download

A long download goes better with a little preparation. Most of it costs nothing:

• Check the space first. A game often needs room for the download and for unpacking it. Running out near the end wastes the whole wait.
• Use a cable for anything over an hour. Wired speeds hold steady, and you skip most of the Wi-Fi losses above.
• Pause the other big users. Cloud backups, game updates on a console and 4K streams all compete for the same line.
• Start it overnight. If the calculator says hours, let it run while nobody else needs the connection.
• Keep the device awake. A laptop that sleeps or a phone that locks can pause the download until you come back.

Download speed against upload speed

On many home plans, uploads run far slower than downloads. Even the FCC's minimum benchmark for fixed broadband asks for 100 Mbps down, but only 20 Mbps up.

That matters whenever a file travels between two people. The sender's upload is usually the slow half, and the recipient's download only starts to matter on a slow line. Use this page for the receiving end and the upload calculator for the sending end.

When you're the one sending the file

Your recipient's download speed sets how long they wait for anything you send. SendTheStuff will send up to 5 GB in one transfer, holding up to 1,000 files. A SendTheStuff link will work for 14 days, so a slow connection can start the download whenever suits it. At 25 Mbps, a full 5 GB transfer is about 27 minutes of their time.

SendTheStuff's free version will allow 10 transfers or 20 GB in any rolling 30 days, whichever comes first. SendTheStuff will let you share each link with the Copy, Email, Messages and Share buttons.

Your side of the trip is the upload, which is often the slower half. The upload time calculator works that half out.

Until SendTheStuff launches

To get a big file to someone today, upload it to a cloud drive you already use and send the link. Before you do, check both halves of the wait: your upload with the upload time calculator, and their download here. If the file is a video, the video file size calculator tells you how big it will be first.